chore: import upstream snapshot with attribution

tests/kg/json_impl/test_write_json_optimization.py

@@ -0,0 +1,490 @@
+"""
+Test suite for write_json optimization
+
+This test verifies:
+1. Fast path works for clean data (no sanitization)
+2. Slow path applies sanitization for dirty data
+3. Sanitization is done during encoding (memory-efficient)
+4. Reloading updates shared memory with cleaned data
+"""
+
+import os
+import json
+import tempfile
+import pytest
+from lightrag.utils import (
+    write_json,
+    load_json,
+    SanitizingJSONEncoder,
+    sanitize_text_for_encoding,
+)
+
+
+@pytest.mark.offline
+class TestWriteJsonOptimization:
+    """Test write_json optimization with two-stage approach"""
+
+    def test_fast_path_clean_data(self):
+        """Test that clean data takes the fast path without sanitization"""
+        clean_data = {
+            "name": "John Doe",
+            "age": 30,
+            "items": ["apple", "banana", "cherry"],
+            "nested": {"key": "value", "number": 42},
+        }
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            # Write clean data - should return False (no sanitization)
+            needs_reload = write_json(clean_data, temp_file)
+            assert not needs_reload, "Clean data should not require sanitization"
+
+            # Verify data was written correctly
+            loaded_data = load_json(temp_file)
+            assert loaded_data == clean_data, "Loaded data should match original"
+        finally:
+            os.unlink(temp_file)
+
+    def test_slow_path_dirty_data(self):
+        """Test that dirty data triggers sanitization"""
+        # Create data with surrogate characters (U+D800 to U+DFFF)
+        dirty_string = "Hello\ud800World"  # Contains surrogate character
+        dirty_data = {"text": dirty_string, "number": 123}
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            # Write dirty data - should return True (sanitization applied)
+            needs_reload = write_json(dirty_data, temp_file)
+            assert needs_reload, "Dirty data should trigger sanitization"
+
+            # Verify data was written and sanitized
+            loaded_data = load_json(temp_file)
+            assert loaded_data is not None, "Data should be written"
+            assert loaded_data["number"] == 123, "Clean fields should remain unchanged"
+            # Surrogate character should be removed
+            assert "\ud800" not in loaded_data["text"], (
+                "Surrogate character should be removed"
+            )
+        finally:
+            os.unlink(temp_file)
+
+    def test_sanitizing_encoder_removes_surrogates(self):
+        """Test that SanitizingJSONEncoder removes surrogate characters"""
+        data_with_surrogates = {
+            "text": "Hello\ud800\udc00World",  # Contains surrogate pair
+            "clean": "Clean text",
+            "nested": {"dirty_key\ud801": "value", "clean_key": "clean\ud802value"},
+        }
+
+        # Encode using custom encoder
+        encoded = json.dumps(
+            data_with_surrogates, cls=SanitizingJSONEncoder, ensure_ascii=False
+        )
+
+        # Verify no surrogate characters in output
+        assert "\ud800" not in encoded, "Surrogate U+D800 should be removed"
+        assert "\udc00" not in encoded, "Surrogate U+DC00 should be removed"
+        assert "\ud801" not in encoded, "Surrogate U+D801 should be removed"
+        assert "\ud802" not in encoded, "Surrogate U+D802 should be removed"
+
+        # Verify clean parts remain
+        assert "Clean text" in encoded, "Clean text should remain"
+        assert "clean_key" in encoded, "Clean keys should remain"
+
+    def test_nested_structure_sanitization(self):
+        """Test sanitization of deeply nested structures"""
+        nested_data = {
+            "level1": {
+                "level2": {
+                    "level3": {"dirty": "text\ud800here", "clean": "normal text"},
+                    "list": ["item1", "item\ud801dirty", "item3"],
+                }
+            }
+        }
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            needs_reload = write_json(nested_data, temp_file)
+            assert needs_reload, "Nested dirty data should trigger sanitization"
+
+            # Verify nested structure is preserved
+            loaded_data = load_json(temp_file)
+            assert "level1" in loaded_data
+            assert "level2" in loaded_data["level1"]
+            assert "level3" in loaded_data["level1"]["level2"]
+
+            # Verify surrogates are removed
+            dirty_text = loaded_data["level1"]["level2"]["level3"]["dirty"]
+            assert "\ud800" not in dirty_text, "Nested surrogate should be removed"
+
+            # Verify list items are sanitized
+            list_items = loaded_data["level1"]["level2"]["list"]
+            assert "\ud801" not in list_items[1], (
+                "List item surrogates should be removed"
+            )
+        finally:
+            os.unlink(temp_file)
+
+    def test_unicode_non_characters_removed(self):
+        """Test that Unicode non-characters (U+FFFE, U+FFFF) don't cause encoding errors
+
+        Note: U+FFFE and U+FFFF are valid UTF-8 characters (though discouraged),
+        so they don't trigger sanitization. They only get removed when explicitly
+        using the SanitizingJSONEncoder.
+        """
+        data_with_nonchars = {"text1": "Hello\ufffeWorld", "text2": "Test\uffffString"}
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            # These characters are valid UTF-8, so they take the fast path
+            needs_reload = write_json(data_with_nonchars, temp_file)
+            assert not needs_reload, "U+FFFE/U+FFFF are valid UTF-8 characters"
+
+            loaded_data = load_json(temp_file)
+            # They're written as-is in the fast path
+            assert loaded_data == data_with_nonchars
+        finally:
+            os.unlink(temp_file)
+
+    def test_mixed_clean_dirty_data(self):
+        """Test data with both clean and dirty fields"""
+        mixed_data = {
+            "clean_field": "This is perfectly fine",
+            "dirty_field": "This has\ud800issues",
+            "number": 42,
+            "boolean": True,
+            "null_value": None,
+            "clean_list": [1, 2, 3],
+            "dirty_list": ["clean", "dirty\ud801item"],
+        }
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            needs_reload = write_json(mixed_data, temp_file)
+            assert needs_reload, (
+                "Mixed data with dirty fields should trigger sanitization"
+            )
+
+            loaded_data = load_json(temp_file)
+
+            # Clean fields should remain unchanged
+            assert loaded_data["clean_field"] == "This is perfectly fine"
+            assert loaded_data["number"] == 42
+            assert loaded_data["boolean"]
+            assert loaded_data["null_value"] is None
+            assert loaded_data["clean_list"] == [1, 2, 3]
+
+            # Dirty fields should be sanitized
+            assert "\ud800" not in loaded_data["dirty_field"]
+            assert "\ud801" not in loaded_data["dirty_list"][1]
+        finally:
+            os.unlink(temp_file)
+
+    def test_empty_and_none_strings(self):
+        """Test handling of empty and None values"""
+        data = {
+            "empty": "",
+            "none": None,
+            "zero": 0,
+            "false": False,
+            "empty_list": [],
+            "empty_dict": {},
+        }
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            needs_reload = write_json(data, temp_file)
+            assert not needs_reload, (
+                "Clean empty values should not trigger sanitization"
+            )
+
+            loaded_data = load_json(temp_file)
+            assert loaded_data == data, "Empty/None values should be preserved"
+        finally:
+            os.unlink(temp_file)
+
+    def test_specific_surrogate_udc9a(self):
+        """Test specific surrogate character \\udc9a mentioned in the issue"""
+        # Test the exact surrogate character from the error message:
+        # UnicodeEncodeError: 'utf-8' codec can't encode character '\\udc9a'
+        data_with_udc9a = {
+            "text": "Some text with surrogate\udc9acharacter",
+            "position": 201,  # As mentioned in the error
+            "clean_field": "Normal text",
+        }
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            # Write data - should trigger sanitization
+            needs_reload = write_json(data_with_udc9a, temp_file)
+            assert needs_reload, "Data with \\udc9a should trigger sanitization"
+
+            # Verify surrogate was removed
+            loaded_data = load_json(temp_file)
+            assert loaded_data is not None
+            assert "\udc9a" not in loaded_data["text"], "\\udc9a should be removed"
+            assert loaded_data["clean_field"] == "Normal text", (
+                "Clean fields should remain"
+            )
+        finally:
+            os.unlink(temp_file)
+
+    def test_migration_with_surrogate_sanitization(self):
+        """Test that migration process handles surrogate characters correctly
+
+        This test simulates the scenario where legacy cache contains surrogate
+        characters and ensures they are cleaned during migration.
+        """
+        # Simulate legacy cache data with surrogate characters
+        legacy_data_with_surrogates = {
+            "cache_entry_1": {
+                "return": "Result with\ud800surrogate",
+                "cache_type": "extract",
+                "original_prompt": "Some\udc9aprompt",
+            },
+            "cache_entry_2": {
+                "return": "Clean result",
+                "cache_type": "query",
+                "original_prompt": "Clean prompt",
+            },
+        }
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            # First write the dirty data directly (simulating legacy cache file)
+            # Use custom encoder to force write even with surrogates
+            with open(temp_file, "w", encoding="utf-8") as f:
+                json.dump(
+                    legacy_data_with_surrogates,
+                    f,
+                    cls=SanitizingJSONEncoder,
+                    ensure_ascii=False,
+                )
+
+            # Load and verify surrogates were cleaned during initial write
+            loaded_data = load_json(temp_file)
+            assert loaded_data is not None
+
+            # The data should be sanitized
+            assert "\ud800" not in loaded_data["cache_entry_1"]["return"], (
+                "Surrogate in return should be removed"
+            )
+            assert "\udc9a" not in loaded_data["cache_entry_1"]["original_prompt"], (
+                "Surrogate in prompt should be removed"
+            )
+
+            # Clean data should remain unchanged
+            assert loaded_data["cache_entry_2"]["return"] == "Clean result", (
+                "Clean data should remain"
+            )
+
+        finally:
+            os.unlink(temp_file)
+
+    def test_empty_values_after_sanitization(self):
+        """Test that data with empty values after sanitization is properly handled
+
+        Critical edge case: When sanitization results in data with empty string values,
+        we must use 'if cleaned_data is not None' instead of 'if cleaned_data' to ensure
+        proper reload, since truthy check on dict depends on content, not just existence.
+        """
+        # Create data where ALL values are only surrogate characters
+        all_dirty_data = {
+            "key1": "\ud800\udc00\ud801",
+            "key2": "\ud802\ud803",
+        }
+
+        with tempfile.NamedTemporaryFile(mode="w", delete=False, suffix=".json") as f:
+            temp_file = f.name
+
+        try:
+            # Write dirty data - should trigger sanitization
+            needs_reload = write_json(all_dirty_data, temp_file)
+            assert needs_reload, "All-dirty data should trigger sanitization"
+
+            # Load the sanitized data
+            cleaned_data = load_json(temp_file)
+
+            # Critical assertions for the edge case
+            assert cleaned_data is not None, "Cleaned data should not be None"
+            # Sanitization removes surrogates but preserves keys with empty values
+            assert cleaned_data == {
+                "key1": "",
+                "key2": "",
+            }, "Surrogates should be removed, keys preserved"
+            # This dict is truthy because it has keys (even with empty values)
+            assert cleaned_data, "Dict with keys is truthy"
+
+            # Test the actual edge case: empty dict
+            empty_data = {}
+            needs_reload2 = write_json(empty_data, temp_file)
+            assert not needs_reload2, "Empty dict is clean"
+
+            reloaded_empty = load_json(temp_file)
+            assert reloaded_empty is not None, "Empty dict should not be None"
+            assert reloaded_empty == {}, "Empty dict should remain empty"
+            assert not reloaded_empty, (
+                "Empty dict evaluates to False (the critical check)"
+            )
+
+        finally:
+            os.unlink(temp_file)
+
+
+@pytest.mark.offline
+class TestSanitizeTextForEncoding:
+    """Direct unit tests for sanitize_text_for_encoding function."""
+
+    def test_empty_string_returns_empty(self):
+        assert sanitize_text_for_encoding("") == ""
+
+    def test_none_like_falsy_returns_as_is(self):
+        # The function checks `if not text`, so empty string returns early
+        assert sanitize_text_for_encoding("") == ""
+
+    def test_whitespace_only_returns_empty(self):
+        assert sanitize_text_for_encoding("   ") == ""
+
+    def test_clean_text_unchanged(self):
+        assert sanitize_text_for_encoding("hello world") == "hello world"
+
+    def test_strips_leading_trailing_whitespace(self):
+        assert sanitize_text_for_encoding("  hello  ") == "hello"
+
+    def test_lone_surrogate_removed(self):
+        assert sanitize_text_for_encoding("hello\ud800world") == "helloworld"
+
+    def test_lone_surrogate_with_replacement_char(self):
+        assert (
+            sanitize_text_for_encoding("hello\ud800world", replacement_char="?")
+            == "hello?world"
+        )
+
+    def test_surrogate_range_boundaries(self):
+        # U+D800 and U+DFFF are the surrogate range boundaries
+        assert "\ud800" not in sanitize_text_for_encoding("\ud800")
+        assert "\udfff" not in sanitize_text_for_encoding("\udfff")
+
+    def test_non_characters_fffe_ffff_removed(self):
+        # U+FFFE and U+FFFF are included in _SURROGATE_PATTERN
+        assert sanitize_text_for_encoding("a\ufffeb") == "ab"
+        assert sanitize_text_for_encoding("a\uffffb") == "ab"
+
+    def test_html_entities_unescaped(self):
+        assert sanitize_text_for_encoding("&") == "&"
+        assert sanitize_text_for_encoding("&lt;p&gt;") == "<p>"
+        assert sanitize_text_for_encoding("&quot;hello&quot;") == '"hello"'
+
+    def test_html_entity_that_becomes_surrogate_is_removed(self):
+        # &#xD800; — Python's html.unescape follows HTML5 spec and maps surrogate code
+        # points to U+FFFD (replacement character), so \uD800 never appears in output.
+        # Either way the result must not contain an actual lone surrogate.
+        result = sanitize_text_for_encoding("&#xD800;")
+        assert "\ud800" not in result
+
+    def test_control_chars_removed(self):
+        # C0 control characters (excluding \t \n \r)
+        assert sanitize_text_for_encoding("\x01hello\x1fworld") == "helloworld"
+        assert sanitize_text_for_encoding("\x00null") == "null"
+        assert sanitize_text_for_encoding("del\x7f") == "del"
+
+    def test_control_chars_with_replacement_char(self):
+        # replacement_char must apply to control chars, not just surrogates.
+        # Note: \x1f is treated as Unicode whitespace by Python's str.strip(),
+        # so place control chars in the middle to avoid them being stripped first.
+        result = sanitize_text_for_encoding("a\x01b\x08c", replacement_char="?")
+        assert result == "a?b?c"
+
+    def test_common_whitespace_preserved(self):
+        # \t, \n, \r must NOT be removed (excluded from control char pattern)
+        assert sanitize_text_for_encoding("line1\nline2") == "line1\nline2"
+        assert sanitize_text_for_encoding("col1\tcol2") == "col1\tcol2"
+        assert sanitize_text_for_encoding("line1\rline2") == "line1\rline2"
+
+    def test_c1_control_chars_not_removed(self):
+        # \x80-\x9F range must NOT be removed (restored original behavior).
+        # These are valid in Latin-1 encoded European language text.
+        result = sanitize_text_for_encoding("caf\x85e")
+        assert "\x85" in result
+
+    def test_replacement_char_default_is_deletion(self):
+        # Default replacement_char="" means characters are deleted, not replaced
+        assert sanitize_text_for_encoding("\ud800hello\x01") == "hello"
+
+    def test_mixed_issues_in_one_string(self):
+        # Surrogate + control char + HTML entity + clean text
+        text = "\ud800&amp;\x01clean"
+        result = sanitize_text_for_encoding(text)
+        assert result == "&clean"
+
+    def test_large_text_with_scattered_surrogates(self):
+        # Regression guard: regex must handle large inputs correctly
+        clean_segment = "a" * 10000
+        text = f"prefix\ud800{clean_segment}\udfffsuffix"
+        result = sanitize_text_for_encoding(text)
+        assert "\ud800" not in result
+        assert "\udfff" not in result
+        assert clean_segment in result
+
+
+if __name__ == "__main__":
+    # Run tests
+    test = TestWriteJsonOptimization()
+
+    print("Running test_fast_path_clean_data...")
+    test.test_fast_path_clean_data()
+    print("✓ Passed")
+
+    print("Running test_slow_path_dirty_data...")
+    test.test_slow_path_dirty_data()
+    print("✓ Passed")
+
+    print("Running test_sanitizing_encoder_removes_surrogates...")
+    test.test_sanitizing_encoder_removes_surrogates()
+    print("✓ Passed")
+
+    print("Running test_nested_structure_sanitization...")
+    test.test_nested_structure_sanitization()
+    print("✓ Passed")
+
+    print("Running test_unicode_non_characters_removed...")
+    test.test_unicode_non_characters_removed()
+    print("✓ Passed")
+
+    print("Running test_mixed_clean_dirty_data...")
+    test.test_mixed_clean_dirty_data()
+    print("✓ Passed")
+
+    print("Running test_empty_and_none_strings...")
+    test.test_empty_and_none_strings()
+    print("✓ Passed")
+
+    print("Running test_specific_surrogate_udc9a...")
+    test.test_specific_surrogate_udc9a()
+    print("✓ Passed")
+
+    print("Running test_migration_with_surrogate_sanitization...")
+    test.test_migration_with_surrogate_sanitization()
+    print("✓ Passed")
+
+    print("Running test_empty_values_after_sanitization...")
+    test.test_empty_values_after_sanitization()
+    print("✓ Passed")
+
+    print("\n✅ All tests passed!")